Code switching (CS) (or language mixing) generally takes place in bilingual children's utterances, even if their parents adhere to the "one parent-one language" principle. The present case study of a Japanese-Chinese bilingual infant provides both quantitative and qualitative analyses on the impact of input on output, as manifested in CS. The database consists of the transcription of 12 hours of audio recordings, selected out of nearly 130 hours of recordings of an infant from the age of 2;1 to 3;0. The quantitative analysis exhibits some influence of parental input on the subject's output in regard to CS. In Qualitative Analysis A, the parental discourse strategy toward the child's CS does account for the overall high ratio of output CS. However, the parental adjustment of input strategies contradicts the present data of output. Qualitative Analysis B concerns the notion of language dominance in terms of intra-sentential CS. Our findings show that, in spite of the absolute Chinese dominance evident in the parental input, the child maintains a strong Japanese-dominant output. Hence, as far as CS is concerned, this study obtains little evidence of qualitative influence of parental input on the child's output. Instead of parental input, language dominance can better account for the increased trend of the child's output CS. (Contains 9 figures, 10 tables, and 10 notes.)